Hundreds of people have been killed in far-western Xinjiang in the past two years, most in violence between the Muslim Uighur people, who call the region home, and ethnic majority Han Chinese.

The government has also blamed attacks in other parts of China, including Beijing, on Islamist militants from Xinjiang.

The Xinjiang regional discipline inspection committee said in a statement late on Thursday those being investigated included six senior public security officials from Hotan and Karakax counties in Xinjiang’s south, as well as the former deputy party secretary of Xinjiang’s education department.

All seven were being investigated for “serious disciplinary violations”, it said, using the usual government euphemism for corruption.

It did not provide further details and it was not possible to reach any of them for comment.

Hotan and Karakax have been at the frontline of what China terms its war on terror.

In December, attackers drove a vehicle into a government building in Karakax, setting off an explosive device and using knives to kill two people before all three assailants were shot dead. The incident was described by Chinese state media as a terrorist attack.

Last month, another three “violent terror” suspects were shot dead by police in Hotan.

The government anti-corruption watchdog’s statement did not specify the ethnicity of the seven officials under investigation, but all appeared to have Uighur names.

Dilxat Raxit, a spokesman for exile group the World Uyghur Congress, said the mass removal of senior Uighur public security personnel was designed to eliminate any lingering obstruction to the strengthened monitoring and repression of Uighurs.

“Even though they acted as Chinese executors of repression and monitoring of the Uighurs, they themselves could not escape China’s hostile defences,” he said in an emailed statement.

On Friday, the anti-graft watchdog said one of its former senior officials in Xinjiang, Han Xincheng, had also been put under investigation for suspected corruption, though it likewise gave no details.

Han had worked in Xinjiang’s party discipline division from 1984 until 2015, according to his official biography. He is from the ethnic majority Han.